Flexible reinforced tubular conduits are in wide use throughout industry whereby numerous manufacturers are engaged in making and selling such conduits, resulting in a highly competitive industry.
Conduits of this type are often used as vacuum cleaner hoses or conduits and a typical vacuum cleaner conduit is made of a reinforcing wire which has a plastic sleeve therearound and is formed in a continuous non-rotating helical coil having axially spaced coils or turns and a compatible plastic tube is extruded therearound and bonded to the outside surface of the wire sleeve to form a reinforced conduit. This type of conduit is a flexible vacuum cleaner conduit in its simplest form; however, it will be appreciated that additional reinforcements, such as fabric or other reinforcements, may be placed concentrically around the tube in one or more layers and in accordance with techniques known in the art.
The basic problem encountered with apparatus proposed heretobefore in continuously forming such flexible conduits is that the reinforcing wire which is plastic sleeve covered and the plastic tube ordinarily extruded therearound are not suitably supported internally throughout the entire fabrication cycle comprised of helically coiling the wire, extruding a plastic tube around the coiled wire causing bonding of the tube and wire to define a conduit, and cooling the conduit whereby the coil diameter of the helically coiled wire cannot be precisely controlled and the wall thickness and diameter of the extruded tube cannot be precisely controlled resulting in a conduit which has a non-uniform wall thickness and thus weak areas at various locations therealong.